The technical field generally relates to engine control systems diagnostics and, in particular, to engine control systems using torque actuation.
Spark ignited (SI) engines can be controlled differently than compression ignited (CI) engines. For example, SI engines typically attempt to maintain a stoichiometric air to fuel ratio (AFR). Torque from an SI engine is primarily controlled through control of air. In contrast, the AFR for CI engines can vary from the stoichiometric AFR. Accordingly, fuel can be controlled independent of air, introducing a control not available on homogenous charge SI engines. Furthermore, gasoline direct injection (GDI) SI engines can be operated with stratified charges, i.e. with varying AFR. Thus, the control of torque can vary based on engine structure.
Therefore, further technological developments are desirable in this area.